Magnetic flux creep in HTSC and Anderson-Kim theory (Review Article)

Abstract

Theoretical results and experimental data on flux creep in high-temperature superconductors (HTSC) are analyzed in this review paper. When reviewing experimental work, the main attention is paid to the most striking experimental results which have had a major impact on the study of flux creep in HTSC. On the other hand, the analysis of theoretical results is focused on the studies which explain the features of flux creep by introducing modifications to the Anderson-Kim (AK) theory, i.e., on the studies that have not received sufficient attention earlier. However, it turned out that the modified AK theory could explain a number of features of flux creep in HTSC: the scaling behavior of current-voltage curves in HTSC, the finite rate of flux creep at ultralow temperatures, the logarithmic dependence of the effective pinning potential on the transport current and its decrease with temperature. The harmonic potential field which is used in this approach makes it possible to solve accurately both the problem of viscous vortex motion and the problem of thermally activated flux creep in this magnetic field. Moreover, the energy distribution of pinning potential and the interaction of vortices with each other are also taken into account in the approach. Thus, the modification of the AK theory consists, essentially, in its refinement and achieving a more realistic approximation.